The touch screen technology has been widely used in man-computer interaction. Compared to the capacitive touch screen, the resistive touch screen is widely used in various devices due to the characteristics of the simple structure, the low cost, the good stability and so on. The screen body of the resistive touch screen is made by a layer of glass or organic glass as a basic layer, and the external surface of the basic layer is coated with a transparent conducting layer, then the conducting layer is covered with a plastic layer with a hardened, smooth and scratch-resistant external surface. The inner surface of the basic layer is also coated with a transparent conducting layer. For the convenience of presentation, the conducting layer of the inner surface and external surface of the basic layer are called the first conducting layer panel and the second conducting layer panel respectively. There are a plurality of small and transparent isolation point between the first conducting layer panel and the second conducting layer panel to separate thereby. There is an insulation between the first conducting layer panel and the second conducting layer panel. FIG. 1 shows the single-point touching diagram of the resistive touch screen, wherein XL, XR, YU, YD are electrical connection ends which could connect the first conducting layer panel of the resistive touch screen to the Y conducting layer. XL and XR jointly form the X axis of a coordinates which sets on the surface screen of the resistive touch screen, and YU and YD form the Y axis of this coordinates.
The user touches the screen of the touch screen by finger. When the pressure on the screen of the resistive touch screen is big enough, the first conducting layer panel and the second conducting layer panel contact at Touching Point P and then conduct the current. FIG. 2 shows the equivalent circuit diagram of the resistive touch screen shown by FIG. 1. Referring to FIGS. 1 and 2, Rxl and Rxr represent the two parts of the equivalent resistor of the first conducting layer panel divided by Touching Point P. Yyu and Yyd represent the two parts of the equivalent resistor of the second conducting layer panel divided by Touching Point P. Rz represents the touch resistance at Touching Point P of the first conducting layer panel and the second conducting layer panel.
In specific applications, the total resistance of the first conducting layer panel and the second conducting layer panel is known. Based on the proportional relationship between the voltage and the resistance, if YU is connected to the positive voltage as reference voltage, and YD is grounded, it gets the voltage digital signal Vadcx of a test point X which is in the XR side by sampling the voltage and performing analog-to-digital conversion by an analog to digital converter (“ADC”, hereafter), and it obtains the voltage value of Touching Point P on the first conducting layer panel; Likewise, if XL is connected to the positive voltage as reference voltage, and XR is grounded, it gets the voltage digital signal Vadcy of a test point X which is in the XR side by sampling the voltage and performing analog-to-digital conversion by ADC, and it obtains the voltage value of Touching Point P on the Y conducting layer panel. As the resistance of the first conducting layer panel and the second conducting layer panel is in the uniform level, the X position and Y position of Touching Point P can be obtained according to the Vadcx and Vadcy.
However, in the process of realizing the present invention, the applicant found that the prior art exists at least the following problems:
As single-point touching just generates a single voltage value to each axis on the resistive touch screen, it can accurately identify the position of the touching point. If there is a second touching point on the resistive touch screen, there will be two voltage values in each axis. These two voltage value can be generated by double-point touching which are on different positions. At that moment, the resistive touch screen can not get the position of the two touching points accurately. Therefore, it can only realize the single-point touching detection on the resistive touch screen based on the prior art, while it can not provide a double-point touching detection for the resistive touch screen, thus it limits the application of the resistive touch screen.